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path: root/drivers/tty/rpmsg_tty.c
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2022-01-26tty: rpmsg: Fix race condition releasing tty portArnaud Pouliquen
The tty_port struct is part of the rpmsg_tty_port structure. The issue is that the rpmsg_tty_port structure is freed on rpmsg_tty_remove while it is still referenced in the tty_struct. Its release is not predictable due to workqueues. For instance following ftrace shows that rpmsg_tty_close is called after rpmsg_tty_release_cport: nr_test.sh-389 [000] ..... 212.093752: rpmsg_tty_remove <-rpmsg_dev_ remove cat-1191 [001] ..... 212.095697: tty_release <-__fput nr_test.sh-389 [000] ..... 212.099166: rpmsg_tty_release_cport <-rpm sg_tty_remove cat-1191 [001] ..... 212.115352: rpmsg_tty_close <-tty_release cat-1191 [001] ..... 212.115371: release_tty <-tty_release_str As consequence, the port must be free only when user has released the TTY interface. This path : - Introduce the .destruct port tty ops function to release the allocated rpmsg_tty_port structure. - Introduce the .hangup tty ops function to call tty_port_hangup. - Manages the tty port refcounting to trig the .destruct port ops, - Introduces the rpmsg_tty_cleanup function to ensure that the TTY is removed before decreasing the port refcount. Fixes: 7c0408d80579 ("tty: add rpmsg driver") Cc: stable <stable@vger.kernel.org> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Link: https://lore.kernel.org/r/20220104163545.34710-1-arnaud.pouliquen@foss.st.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-26tty: rpmsg: Define tty name via constant string literalAndy Shevchenko
Driver uses already twice the same string literal. Define it in one place, so every user will have this name consistent. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20211025135148.53944-5-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-26tty: rpmsg: Add pr_fmt() to prefix messagesAndy Shevchenko
Make all messages to be prefixed in a unified way. Add pr_fmt() to achieve this. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20211025135148.53944-4-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-26tty: rpmsg: Use dev_err_probe() in ->probe()Andy Shevchenko
It's fine to use dev_err_probe() in ->probe() even if we know it won't be deferred. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20211025135148.53944-3-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-26tty: rpmsg: Unify variable used to keep an error codeAndy Shevchenko
In some ret is used, in the other err. Let's unify it across the driver. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20211025135148.53944-2-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-26tty: rpmsg: Assign returned id to a local variableAndy Shevchenko
Instead of putting garbage in the data structure, assign allocated id or an error code to a temporary variable. This makes code cleaner. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20211025135148.53944-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-21tty: add rpmsg driverArnaud Pouliquen
This driver exposes a standard TTY interface on top of the rpmsg framework through a rpmsg service. This driver supports multi-instances, offering a /dev/ttyRPMSGx entry per rpmsg endpoint. Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Link: https://lore.kernel.org/r/20211015094701.5732-3-arnaud.pouliquen@foss.st.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>